The present invention relates generally to the removal of an alginate from a cutaneous substrate using an aqueous solution of at least one chelating agent. While chelants have been used industrially to remove alginates from substrates such as floors and vessels, their use in the field of wound management is believed to be novel.
The instant chelant compositions are of particular benefit in the field of wound management, where alginate wound dressings are commonly used. In addition to chelating agents, these compositions may also contain physiological salts and one or more EO/PO-type surfactants. The preferred compositions of this invention are non-cytotoxic.
Alginate fibres have been known for some time as being useful in the preparation of surgical dressings. For example, United Kingdom Patent No. 653341 describes surgical dressings formed from fibres of calcium alginate. This reference recognizes that a failing of calcium alginate fibres is their relative insolubility in water or wound exudate matter. Bonniksen in GB-A-653341 therefore proposed that a proportion of the calcium ions in calcium alginate be replaced by sodium cations, since sodium alginate was known to be more soluble than calcium alginate. The resulting process has become known as "conversion" of calcium alginate to form a mixed salt alginate.
As used herein, the term "alginate" refers to any salt of alginic acid. In particular, the class of alginates includes but is not limited to, calcium, magnesium, sodium and potassium alginates, and mixtures thereof. Alginate wound dressings include any alginate-containing dressings used in the fields of human or animal wound management.
For example, EP 433354 discloses the use of mixed salt alginates in the manufacture of wound dressings. In such dressings, the mixed salt alginate forms the wound contact pad. U.K. 8815132 discloses the use of mixed alginate salt fibre dressings on skin wounds. KALTOSTAT.RTM. is a highly absorbent alginate wound dressing which is commercially available from Calgon Vestal Laboratories.
If dry, alginate wound dressings are generally removed by simply soaking the dressing with saline for several minutes. Though this procedure tends to soften alginate dressings, subsequent removal of the dressing may still be difficult. By contrast, the instant chelant compositions solubilize or dissolve, at least to some extent, alginates, thereby facilitating removal of alginates from cutaneous substrates to which they are affixed. This method of removal is not known or suggested in the art.
As used herein, the term "chelating agent" refers to any compound having the ability to complex, solubilize or bind a base metal present in an alginate fiber, particularly a calcium, magnesium, sodium or potassium ion. As such, the term chelating agent as used herein is synonymous, inter alia, with the following terms: chelant, sequestrant, sequestering agent and complexing agent. In theory, any chelating agent which solubilizes an alginate can be used in the instant compositions.
As mentioned above, the instant compositions may contain one or more physiological salts and one or more surfactants in addition to the chelating agent. While copending and commonly assigned application U.S. patent application Ser. No. 446,276 discloses the use of aqueous compositions comprising physiological salts and EO/PO block copolymers in wound management, the presence of chelating agents is not disclosed. Exemplary of such compositions is the product SAF-CLENS.RTM. which is commercially available from Calgon Vestal Laboratories.
Also, U.S. Pat. No. 29,909 to Kurtz discloses a method of cleansing wounds which utilizes aqueous detergent solutions of ethylene oxide (EO)/propylen oxide (PO) block copolymers. The block copolymers of Kurtz are commercially available as PLURONIC.RTM. Polyols from BASF Kurtz discloses that his designated EO/PO polymers do not impair the ability of a wound being treated to resist infection. The claimed Kurtz wound cleansing compositions consist of an aqueous detergent solution of at least about 10% of an EO/PO block copolymer having an EO/PO ratio of at least 3:1 and a molecular weight of from about 5,000 to about 15,000.
A wound cleanser known as SHUR CLENS.RTM., which is commercially available from Calgon-Vestal Laboratories, represents a commercial embodiment of a wound cleansing composition disclosed by Kurtz.